// Closure of Underground Cavities, Special solutions for the mining and construction industry

KOMPASS

Compaction of salt gravel for secure containment

The R&D project KOMPASS (FKZ 02E 11708) resulted from the safety requirement of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) to isolate radioactive waste in an effectively sealed geological area. In the case of the host rock salt, salt gravel backfill has the potential, when fully compacted, to achieve a barrier effect comparable to that of intact salt barriers, thereby restoring the natural salt barrier. This property was not previously investigated in detail because the focus of safety assessment was on limiting the release of radionuclides rather than on their isolation. The previous approach resulted in knowledge gaps regarding the behavior of salt gravel at low porosity. The aim of the KOMPASS project was to develop methods and strategies to close knowledge gaps and thus improve predictions of salt gravel compaction in the low porosity range. The R&D project KOMPASS included the development of methods for experimentally determining salt gravel properties in the low porosity range, improving process understanding, and investigating and further developing existing numerical models. The R&D consortium project KOMPASS, funded by the Federal Ministry for Economic Affairs and Energy, was conducted by BGE TECHNOLOGY GmbH, the Federal Institute for Geosciences and Natural Resources, Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH, Institut für Gebirgsmechanik GmbH, and Technische Universität Clausthal from September 2018 to August 2020. Sandia National Laboratories, USA, were an associated partner in this project.